Its a review about this product
I love Smartwool in general - have several SW tops, they are fantastic for keeping warm but not too warm, as well as avoiding that clammy feeling when coming in from out of the cold. Bought these leggings for extra warmth when outdoors in the winter (occasional winter sports; walking kids to/from school, etc.). The S fit me very well (I am 5' and curvy, usually a S or 4-6 in most brands). The waistband is comfy and fit is overall flattering (as an under-layer). The bottoms worked very well for me - under lined pants, but I have also worn with jeans on 30-deg days - this past weekend, when I was outdoors in 25-degree weather for four hours, sometimes walking, sometimes standing in a medium breeze.
The one drawback I found was that the waistband on these seemed to have a stiff/sharp black filament poking through. Looked like a strand of polyester - thicker and not as flexible as thread. I don't know if it was faulty construction or a piece of extraneous material that had gotten trapped in the seam during sewing, but it was quite uncomfortable. I finally took a pair of pliers and pulled it out (there was about six inches' worth). Does not seem to have affected the rest of the garment, fingers crossed that I will have no more issues. Hopefully this was a one-off problem and not true for any other pairs!